Dromornithidae

Dromornithidae, known as mihirungs (after Tjapwuring Mihirung paringmal, "giant bird") and informally as thunder birds or demon ducks, is an extinct family of large, flightless birds native to Australia from at least the late Oligocene (and perhaps as early as the early Eocene) to the Late Pleistocene. They were long classified in Struthioniformes (the ratites), but are now usually classified as a type of gigantic fowl (Galloanserae). Dromornithids were part of the Australian megafauna. One species, Dromornis stirtoni, was 3 m (9 ft 10 in) tall, making them among the largest birds ever. Only a single species, Genyornis newtoni survived into the Late Pleistocene. They are thought to have been herbivorous.

The scientific name Dromornithidae derives from the Greek words δρομαίος, dromaios ("swift-running") and ὀρνις, ornis ("bird"). The family was named by Max Fürbringer in 1888, citing W. B. Clarke and Gerard Krefft, Owen's separation from "Dromaeus" and Dinornis, and a note by von Haast allying Dromornis with Dromaeus. What the nearest relatives of this group are is a controversial issue. For many years it was thought that dromornithids were related to ratites, such as emus, cassowaries, rheas and ostriches. It is now believed that the similarities between these groups are the result of similar responses to the loss of flight. The latest idea on dromornithid relationships, based on details of the skull, is that they evolved early in the lineage that includes waterfowl (Anseriformes). However, some phylogenetic studies have recovered them as closer to gamefowl (Galliformes).

Below is the general consensus of the phylogeny under the hypothesis that they are members of Anserimorphae.

A 2017 paper concerning the evolution and phylogeny of the giant fowl by Worthy and colleagues have found phylogenetic support in finding the mihirungs to be the sister taxon to Gastornithidae. Worthy et al. (2017) incorporated several new taxa and character traits into existing matrices of Galloanserae resulted in several of their phylogenies to support this grouping. The authors did note the bootstrap support is weakly supported and one of their phylogenies even found gastornithiforms to be stem galliforms instead. These were also weakly supported. Below is a simplified phylogeny showing their one phylogeny supporting gastornithiforms as anserimorphs.

A 2021 study conversely found their internal cranial anatomy more similar to that of galliforms than to anseriforms.

A 2022 study concerning their proteins found them to be sister group to the common group of galliforms and anseriforms.

Two years later, Mclnerney, Blokland and Worthy redescribed the skull morphology and phylogenetic affinity of the dromornithid Genyornis newtoni, finding Dromornithidae as members of Anseriformes, closely related to screamers from South America.

The number of taxa in the Dromornithidae family was recognised as eight species in four genera by 2021, the smallest species was Barawertornis tedfordi, a bird about the size of a modern cassowary, weighing 80 to 95 kg (176 to 209 lb). The two species of Ilbandornis (Ilbandornis lawsoni and Ilbandornis woodburnei) were larger birds, but had more slender legs than the other dromornithids and were similar to ostriches in their build and size. Dromornis planei (the "demon duck of doom") and Genyornis newtoni (the "mihirung") were more heavily built, stood about 2 to 2.5 m (6.6 to 8.2 ft) tall and probably reached weights of 220 to 240 kg (490 to 530 lb). The largest dromornithids were Dromornis australis, from which the family gets its name, and the massive Dromornis stirtoni ("Stirton's thunderbird"). Genyornis is the best known of the genera.^{[citation needed]}